From The New York Times:

It seems to work for the Amish, researchers say in the current issue of Medicine & Science in Sports & Exercise. When they studied an Amish farming community in southern Ontario, they found that obesity was virtually nonexistent. The authors of the study chose the Amish to test a theory that the weight problems of today were associated with a decrease in the physical activities people once had to perform to stay alive. In the Old Order Amish community studied, people get around on foot or by horse and buggy, and their fields are plowed and houses built without benefit of modern machinery. "We were really kind of struck by the tremendous difference in the quantity of activity that they do," said the lead author of the study, Dr. David R. Bassett Jr. of the University of Tennessee. Participants in the study were equipped with pedometers and asked to keep detailed records of their labor over a week. The men reported 52 hours of vigorous or moderate labor, and 12 hours of walking. The women reported 42 hours of vigorous or moderate labor and more than 5 hours of walking. The physical activity was about six times as much as participants reported in a recent survey of modernized nations, the researchers said. Although about a quarter of the Amish were overweight, none of the men were obese, and 9 percent of the women were, despite a traditional diet heavy in meat, eggs, bread and pies.